This invention relates to a method for producing polyaniline in situ in a solid electrolyte capacitor, and more particularly to such a method for producing highly conducting polyaniline in a porous pellet.
Solid electrolyte capacitors have scarcely changed with respect to electrolyte production since their introduction to the market in 1956. The electrolyte of choice then and now is manganese dioxide which is produced within oxidized porous pellets by repeated in situ pyrolytic decompositions of manganous nitrate at temperatures around 300.degree. C. The elevated pyrolysis temperature requires the capacitor to be rated for use in a circuit at a fraction of the voltage used to form the dielectric oxide layer in the pellet.
Efforts to employ electrolytes other than manganese dioxide have centered on TCNQ complexes because of their higher conductivity. However, efforts to commercialize TCNQ capacitors have not progressed notably beyond the initial work of Ross et. al. in U.S. Pat. No. 3,214,648 and U.S. Pat. No. 3,214,650 because the instability of TCNQ complexes makes capacitor production difficult.
More recently, hetrocyclic polymers have been studied; again, because they offer conductivities much higher than manganese dioxide. Again, as with TCNQ complexes, these polymers introduce production difficulties into capacitor manufacture because their wide range of conductivities from conductor to insulator requires stringent controls to ensure useful capacitor electrolytes.